Investigators have not yet confirmed if the candies were tampered with or which substances might have been added, but Naperville North High School students reportedly told authorities the candies contained marijuana.

Edward Hospital doctors treated 12 of the 14 students after they experienced symptoms including increased heart rate, dizziness and dry mouth from consuming the possibly tainted candies, Naperville School District 203 wrote on its Facebook page Tuesday night.

“Each student had varying degrees of discomfort and subsequent treatment,” the district wrote. All students who were treated were eventually released from the hospital.

One Facebook user commented on the police department’s post wondering if the gummy bears consumed were the notorious Haribo sugar-free ones, which online reviewers have complained made them feel ill. But Naperville School District 203’s post suggested otherwise.

The school district urged parents to talk with their children about making healthy choices and seeking out school and community resources available to support the wellbeing of students.

Clarification: Headlines for this article have been amended to reflect that Naperville, where the school is located, is not within Chicago city limits.